U.S. patent application number 10/359157 was filed with the patent office on 2003-09-04 for organic electro-luminescence device and method of manufacturing the same.
Invention is credited to Fukuoka, Nobuhiko, Inoue, Takashi, Nakano, Keiko, Ushifusa, Nobuyuki.
Application Number | 20030164681 10/359157 |
Document ID | / |
Family ID | 27800032 |
Filed Date | 2003-09-04 |
United States Patent
Application |
20030164681 |
Kind Code |
A1 |
Fukuoka, Nobuhiko ; et
al. |
September 4, 2003 |
Organic electro-luminescence device and method of manufacturing the
same
Abstract
A cap surrounding projection is provided on an outer periphery
of a light transmitting cap substrate simultaneously with pixel
separation banks, and a surrounding recess is formed in a position,
opposed to the cap surrounding, projection, on a substrate provided
with emitter elements, the projection and the recess being joined
through a sealant with an absorbent arranged therein. With such
construction, it becomes possible to efficiently take out light
from an emitting layer and to highly accurately seal the substrate
provided with the emitter elements and the light transmitting cap
substrate, thus realizing an organic electro-luminescence device of
high reliability.
Inventors: |
Fukuoka, Nobuhiko; (Ebina,
JP) ; Ushifusa, Nobuyuki; (Yokohama, JP) ;
Inoue, Takashi; (Yokohama, JP) ; Nakano, Keiko;
(Yokohama, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-9889
US
|
Family ID: |
27800032 |
Appl. No.: |
10/359157 |
Filed: |
February 6, 2003 |
Current U.S.
Class: |
313/512 |
Current CPC
Class: |
H01L 27/3246 20130101;
H01L 2251/5315 20130101; H01L 51/5246 20130101; H01L 51/5259
20130101; H01L 27/3283 20130101 |
Class at
Publication: |
313/512 |
International
Class: |
H05B 033/00; H05B
033/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2002 |
JP |
2002-055167 |
Claims
We claim:
1. An organic electro-luminescence device comprising an emitter
element forming substrate, a cap substrate, a cap outer-periphery
surrounding rib, and a sealant, and wherein emitter element are
formed on the emitter element forming substrate to have at least an
emitting layer, which is formed in pixel separation banks,
interposed by anode electrodes and cathode electrodes, and the
emitter element forming substrate and the cap substrate are joined
together through the sealant so that the emitter element are
arranged inside the cap outer-periphery surrounding rib formed on
an outer periphery of the cap substrate in a picture-frame
manner.
2. The organic electro-luminescence device according to claim 1,
wherein the emitter element forming substrate and the cap substrate
comprise a light transmitting substrate having a substantially
equivalent physical property.
3. The organic electro-luminescence device according to claim 1,
wherein the cap substrate is formed from a material transmitting
therethrough ultraviolet rays.
4. The organic electro-luminescence device according to claim 1,
wherein an absorbent for absorption of at least gas or moisture is
arranged in a space surrounded by the emitter element forming
substrate, the cap substrate, and the cap outer-periphery
surrounding rib.
5. The organic electro-luminescence device according to claim 4,
wherein the absorbent is arranged in a region not to intercept
emission from the emitter elements.
6. The organic electro-luminescence device according to claim 1,
wherein the cathode electrodes comprise a light transmitting
conductive material.
7. The organic electro-luminescence device according to claim 1,
wherein the cathode electrodes comprise a light transmitting
conductive material and light transmitted through the cathode
electrodes from the emitter elements is observed through the cap
substrate.
8. The organic electro-luminescence device according to claim 1,
wherein positioning ribs arranged outside the emitter elements on
the emitter element forming substrate are joined to the cap
outer-periphery surrounding rib through the absorbent.
9. The organic electro-luminescence device according to claim 1,
wherein the positioning ribs have a greater width than that of the
pixel separation banks.
10. The organic electro-luminescence, device according to claim 1,
wherein the positioning ribs are formed from the same material as
that of the pixel separation banks.
11. The organic electro-luminescence device according to claim 1,
wherein the emitter element forming substrate comprises thin-film
transistors for driving the emitter elements.
12. A method of manufacturing an organic electro-luminescence
device, comprising the steps of: forming emitter elements, which
comprise pixel separation banks for separating an emitting layer,
on an emitter element forming substrate, forming positioning ribs
outside the emitter elements on the emitter element forming
substrate, forming a cap outer-periphery surrounding rib in a
position opposed to the positioning ribs on a cap substrate, and
sealing the emitter element forming substrate and the cap substrate
through a sealant by means of the positioning ribs and the cap
outer-periphery surrounding rib.
13. The method according to claim 12, wherein the step of forming
the pixel separation banks and the step of forming the positioning
ribs are performed in the same processing.
14. The method according to claim 12, wherein in the step of
forming the positioning ribs, the positioning ribs are formed so
that a circumferential size of the positioning ribs is smaller than
an inner circumferential size of the cap outer-periphery
surrounding rib.
15. The method according to claim 12, wherein in the step of
forming the positioning ribs, first positioning ribs and second
positioning ribs provided outside the first positioning ribs are
formed so as to interpose therebetween the cap outer-periphery
surrounding rib.
16. The method according to claim 12, wherein in the step of
forming the positioning ribs, the positioning ribs are formed to
have a greater width than that of the pixel separation banks.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to an organic electro-luminescence
device and a method of manufacturing the same, and more
particularly, to a method of manufacturing a cap having a light
transmissivity and a method of overlapping the cap by
self-alignment.
[0002] Generally, an organic electro-luminescence device is
finished by sequentially implementing the steps of patterning anode
electrodes formed on a glass substrate every element, forming banks
for separating a laminate formed on the anode electrodes every
element, forming hole-introduction layers, which introduce electron
holes from the anode electrodes, in spaces partitioned by the
banks, forming hole-transport layers, which transport electron
holes to emitting layers, selecting elements and forming emitting
layers composed of an organic film for emission in red, green and
blue, forming electron-transport layers, which transport electrons
from cathode electrodes, forming cathode electrodes, which supplies
electrons, and joining a cap to the glass substrate with a sealing
adhesive in order to block these laminates from outside.
[0003] Such organic electro-luminescence device as described in
JP-A-11-176571 cannot maintain emission of predetermined quality
with the lapse of drive time because in spite of airtight sealing
by a cap, under the influence of outside air and moisture, peel is
caused between emitting layers and electrode layers, constituent
materials change in quality, and non-emitting regions called dark
spots are generated.
SUMMARY OF THE INVENTION
[0004] As described above, an atmosphere at the time of sealing and
a way of maintaining a state immediately after sealing in the
future become a problem because of susceptibility to outside air
and moisture. Also, since emitting layers are formed from an
organic material, there is the possibility that gas is generated
after sealing. Therefore, it is essential to perform sealing in a
state of receiving an absorbent capable of absorbing gas generated
and outside air and moisture entering through a sealant.
[0005] Generally, a cap is shaped such that an inner portion is
recessed from an outer periphery thereof to mount therein an
absorbent so that the absorbent does not interfere with emitter
elements composed of emitting layers, electrodes and soon. Ways to
recess an interior of a cap include carving an interior of a glass
plate or quartz plate by means of machining or sand blasting, and
integral molding of a metallic plate or glass plate by means of a
press or the like. In the case of using these caps, there is no
problem when emission is taken out from a side of a substrate, on
which emitting layers are formed.
[0006] In the case where emission is taken out from a side of a
cap, which makes it possible to take out emission at a high
numerical aperture without being affected by interception caused by
wiring on the substrate and drive elements, a surface condition of
the cap possibly causes a problem. That is, with a cap obtained by
the method of carving an interior of a glass plate or quartz plate,
light transmissivity is made low because of work marks present in
the carved interior.
[0007] Also, with a cap obtained in integral molding by means, of a
press, taking-out of emission is impossible with a metal plate, and
surface accuracy of a die is made important with a glass plate
because the surface of the die is transferred to surfaces of the
plate. Maintenance of high surface accuracy is difficult, the
possibility of degradation in light transmissivity is high because
glass surfaces are frosted with deterioration of the die in the
case of mass production. In this manner, a first task is to
manufacture a cap having a high light transmissivity in the case
where emission is taken out from a side of the cap.
[0008] Also, the step of overlapping a cap on a glass substrate, on
which emitting layers of an organic electro-luminescence device are
formed, and sealing them is implemented in a space closed from
outside in order to perform an operation in an atmosphere, from
which an active gas and moisture is removed as far as possible. In
order to overlap the glass substrate, on which emitting layers of
an organic electro-luminescence device are formed, and the cap in
the closed space, the positioning function by means of a camera or
the like is necessary, and further equipments for irradiating
ultraviolet rays for curing of a sealant and heating are also
necessary. Therefore, there is a need of a high-performance
manufacturing apparatus capable of atmosphere adjustment, having a
high close quality, performing positioning while using a camera or
the like for ascertaining, irradiating ultraviolet rays, and
heating, so that installation cost is necessarily increased. A
second task is a need of a high-performance and expensive
manufacturing apparatus.
[0009] Hereupon, the invention has its object to provide an organic
electro-luminescence device having a cap of high light
transmissivity capable of allowing emission to be taken out from a
side of the cap, and a manufacturing method thereof, and to provide
an organic electro-luminescence device, in which a substrate formed
with an organic emitter element and a cap are accurately overlapped
together by means of an apparatus having no positioning function,
and a manufacturing method thereof.
[0010] In order to solve the above problems, the invention provides
an organic electro-luminescence device, in which emitter elements,
in which an organic layer having at least an emitting layer is
formed in pixel separation banks on anode electrodes and interposed
between the anode electrodes and cathode electrodes, are arranged
on a emitter element forming substrate composed of a glass
substrate or the like, and a material transmitting therethrough
ultraviolet rays forms a cap outer-periphery surrounding rib on an
outer periphery of a cap substrate composed of a light transmitting
substrate having an equivalent physical property to that of the
emitter element forming substrate in a picture-frame manner, the
emitter elements being arranged inside the cap outer-periphery
surrounding rib and covered by the cap outer-periphery surrounding
rib and the cap substrate.
[0011] Also, an absorbent for absorption of gas generated or
moisture is arranged between an outside of a region, in which the
emitter elements are formed, on the emitter element forming
substrate opposed to and overlapped on the cap substrate and the
cap outer-periphery surrounding rib provided on the cap substrate
in a picture-frame manner.
[0012] Further, the cathode electrodes are formed from a light
transmitting conductive material and emission generated in the
emitting layer is transmitted through the cathode electrodes so
that light transmitted through the cathode electrodes is seen
through the cap substrate composed of a light transmitting
substrate.
[0013] Also, positioning ribs composed of the same material as that
of the pixel separation banks, which serve to separate the emitting
layer, are provided to surround the emitter elements, and are
larger in width than the pixel separation banks, and the pixel
separation banks and the positioning ribs, which are made different
from each other in film thickness (height) due to a difference in
width, are formed in the same processing.
[0014] Further, circumferential and inner circumferential sizes of
the positioning ribs are smaller or larger than circumferential and
inner circumferential sizes of the cap outer-periphery surrounding
rib, so that when the emitter element forming substrate formed with
the emitter element and the cap composed of the cap substrate and
the cap outer-periphery surrounding rib are overlapped together,
sides of the positioning ribs and sides of the cap outer-periphery
surrounding rib come into contact with each other and so the
positioning ribs serve as a guide when the cap and the emitter
element forming substrate are overlapped together.
[0015] In this manner, according to the invention, the cap
substrate composed of a light transmitting substrate having a
substantially equivalent physical property to that of the emitter
element forming substrate, on which emitter elements are formed, is
used and a surrounding projection is provided on an outer periphery
of the cap substrate in a picture-frame manner, whereby it is
possible to obtain a cap of high light transmissivity having an
area shaped, of which inner portion is recessed from an outer
periphery thereof to receive an absorbent. Further, the absorbent
is mounted between an outside of an area, in which opposed emitter
elements are formed, and the cap outer-periphery surrounding rib
shaped in a picture-frame manner, so that emission is intercepted
only by the cap substrate composed of a light transmitting
substrate and so can be effectively taken out into a cap side.
[0016] Also, since the positioning ribs are formed on the emitter
element forming substrate, on which emitter elements are formed,
together with the pixel separation banks, the positioning ribs can
be formed without positional deviation relative to an area, in
which emitter elements are formed. Circumferential and inner
circumferential sizes of the positioning ribs are alternated with
circumferential and inner circumferential sizes of the cap
outer-periphery surrounding rib, whereby the positioning ribs can
serve as a guide at the time of overlapping and so accurate
overlapping of the cap can be effected with an area, in which
emitter elements are formed, being made a reference, although the
positioning function such as camera or the like is not
provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] These and other features, objects and advantages of the
present invention will become more apparent from the following
description when taken in conjunction with the accompanying
drawings wherein:
[0018] FIG. 1 is a cross sectional view showing the configuration
of members constituting a cap and the positional relationship
between the cap and emitter elements;
[0019] FIGS. 2A and 2B are views illustrating a processing of
simultaneously forming pixel separation banks and positioning
ribs;
[0020] FIGS. 3A to 3G are views illustrating steps of manufacturing
an organic electro-luminescence device according to a first
embodiment;
[0021] FIG. 4 is a cross sectional view showing a final
configuration of an organic electro-luminescence device according
to a second embodiment;
[0022] FIG. 5 is a cross sectional view showing a final
configuration of an organic electro-luminescence device according
to a third embodiment;
[0023] FIGS. 6A to 6G views illustrating steps of manufacturing an
organic electro-luminescence device according to a fourth
embodiment; and
[0024] FIG. 7 is a cross sectional view showing thin-film
transistors according to a sixth embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] An explanation will be given to a first embodiment of an
organic electro-luminescence device of the invention.
[0026] While an organic electro-luminescence device includes a low
molecular system and a polymer system as an organic material used
in portions contributing to emission, the invention puts no
limitation on them and an organic electro-luminescence device, in
which the both are mixed together, will do.
[0027] An organic electro-luminescence device with a low molecular
system is generally composed of glass substrate/anode
electrode/hole-injection layer/hole-transport layer/emitting
layer/electron-transport layer/cathode electrode/cap.
[0028] Meanwhile, an organic electro-luminescence device with a
polymer system is generally composed of glass substrate/anode
electrode/hole-transport layer/emitting layer/cathode
electrode/cap.
[0029] With an organic electro-luminescence device with a polymer
system, a hole-transport layer in some cases has both of
characteristics of hole-injection layer/hole-transport layer in an
organic electro-luminescence device with a low molecular system,
and with an organic electro-luminescence device with a polymer
system, only a cathode electrode in some cases does duty for
electron-transport layer/cathode electrode in an organic
electro-luminescence device with a low molecular system. Also, a
cap and a glass substrate are bonded together with a sealant
therebetween, and mount therein an absorbent for absorption of
moisture and gas. The invention is not limited to materials,
composition or the like used in the embodiment, and the embodiment
is intended for realizing an organic electro-luminescence
device.
[0030] Concrete embodiments of the invention will be described
below in detail with reference to the drawings.
[0031] (First Embodiment)
[0032] FIG. 1 is a cross sectional view showing the configuration
of members constituting a cap according to a first embodiment and
the positional relationship between the cap and emitter elements.
In FIG. 1, the reference numeral 1 denotes an emitter element
forming substrate, 2 a cap substrate, 3 a cap outer-periphery
surrounding rib, 4 a cap, 5 an absorbent, 6 anode electrodes, 7
pixel separation banks, 8 an emission contributing layer, 9 cathode
electrodes, 10 emitter elements, 22 a sealant.
[0033] The emitter element forming substrate 1 is formed from a
glass substrate or the like, and the cap substrate 2 is the same
light transmitting substrate as that of the emitter element forming
substrate 1. The cap 4 is composed of the cap substrate 2 and the
cap outer-periphery surrounding rib 3, and the cap outer-periphery
surrounding rib 3 is formed on an outer periphery of the cap
substrate 2. The emitter elements 10 are composed of the anode
electrodes 6, the pixel separation banks 7, the emission
contributing layer 8, and the cathode electrodes 9, and the cap
outer-periphery surrounding rib 3 is formed in a larger region than
that, in which the emitter elements 10 are formed, to have a
greater thickness than a total of thickness of the absorbent 5 and
the emitter elements 10.
[0034] In addition, the emission contributing layer 8 interposed
between the anode electrodes 6 and the cathode electrodes 9 to
contribute to emission is varied in layer configuration depending
upon the material system (polymer system, low molecular system) of
a luminescent layer as described previously.
[0035] The cap outer-periphery surrounding rib 3 can be formed from
an organic material and an inorganic material. Methods for forming
the rib include a method of straight-writing by means of screen
printing, dispenser or the like, and a method of forming the rib by
coating a material of the cap outer-periphery surrounding rib 3 on
an entire one side of the cap substrate 2 by means of a spinner or
the like, and then removing other portions than an unnecessary
periphery in exposure and development processing.
[0036] The absorbent 5 serves to absorb gas generated from the
emitter elements and outside air and moisture entering from outside
after sealing. Also, the absorbent 5 is mounted outside a region,
in which the emitter elements 10 are formed, and in a region
interposed between inside, surfaces of the cap outer-periphery
surrounding rib 3. Thereby, emission can be effectively taken out
to an outside through the cap substrate 2, which is formed from a
light transmitting substrate, without interrupting emission of the
emitter elements 10.
[0037] FIGS. 2A and 2B are views illustrating a series of
processing when pixel separation banks according to the first
embodiment of the invention and positioning ribs are formed at the
same time. In FIGS. 2A and 2B, the reference numeral 11 denotes a
squeegee, 12 a scraper, 13 a head having a mechanism for holding
and moving the squeegee 11 and the scraper 12 up and down, 14 a
screen form plate, 15 a screen mask, 16 an aperture pattern for
transfer of pixel separation banks, 17 an aperture pattern for
transfer of positioning ribs, 18 ink, 19 a substrate fixing table,
and 20 positioning ribs.
[0038] The squeegee 11 serves to apply ink 18, placed on a surface
of the screen mask 15 on a side of the squeegee, to an opposite
side of the surface, through the aperture pattern 16 for transfer
of pixel separation banks and the aperture pattern 17 for transfer
of positioning ribs.
[0039] The scraper 12 serves to fill the ink 18 into the aperture
pattern 16 for transfer of pixel separation banks and the aperture
pattern 17 for transfer of positioning ribs provided on the screen
mask 15. The squeegee 11 and the scraper 12 are moved up and down
by the head 13 such that at the time of ink filling, the squeegee
11 is lifted and the scraper 12 is lowered to be brought into close
contact with the screen mask 15, and at the time of ink
application, the scraper 12 is lifted and the squeegee 11 is
lowered to be brought into close contact with the screen mask 15.
The screen mask 15 is mounted on the screen form plate 14.
[0040] Apertures in the aperture pattern 17 for transfer of
positioning ribs are necessarily formed to have a larger width of
apertures in the aperture pattern 16 for transfer of pixel
separation banks.
[0041] The reason for this is that the inventors of the present
invention have found that in screen printing, thickness of
application is varied according to a width of apertures in a screen
form plate. Thus the positioning ribs are made thicker than a film
thickness of pixel separation banks, and the aperture pattern 17
for transfer of positioning ribs is greater in width than the
aperture pattern 16 for transfer of pixel separation banks in order
that the positioning ribs be made thicker than a film thickness of
pixel separation banks and be formed in the same printing.
[0042] More specifically, there is a tendency that when apertures
in a screen form plate have a larger width than a certain width, a
coating thickness becomes constant, and as the apertures have a
smaller width than the certain width, the coating thickness
decreases. By making use of this phenomenon, different coating
thickness can be formed in the same printing process and in the
same plane. In addition, this tendency of coating thickness
relative to the line width is varied according to a material of ink
and specifications of a screen form plate.
[0043] In the embodiment, polyimide PP-2000 for screen printing,
manufactured by Central Glass Corporation was used for a material
for pixel separation banks, and the screen form plate was formed by
using No. 500 stainless steel mesh having a wire diameter of 18
.mu.m, an aperture size of 33 .mu.m and a numerical aperture of 42%
and forming on the mesh an emulsion (description of product: NSL)
manufactured by Tokyo Process Service Corporation and having an
excellent solvent resistance, in the film thickness of 30
.mu.m.
[0044] With a combination of the ink material and the screen form
plate, the film thickness was formed to be substantially equal to
the emulsion thickness on the screen form plate in the range of
line width above 150 .mu.m, and the film thickness formed decreased
as the line width became smaller than 150 .mu.m such that the film
thickness was approximately 5 .mu.m for the line width of 20
.mu.m.
[0045] More specifically, in the case where the width of the
aperture pattern 17 for transfer of positioning ribs was made
larger than 150 .mu.m and the width of the pattern 16 for transfer
of pixel separation banks was made 20 .mu.m, positioning ribs
having a film thickness of 30 .mu.m could be formed together with
pixel separation banks having a film thickness of 5 .mu.m. The rib
having a film thickness of around 30 .mu.m is adequately effective
in serving as a positioning guide. In addition, the condition for
simultaneous transfer of different coating thickness in screen
printing is not limited to the above materials and the screen form
plate of the above specifications.
[0046] As shown in FIG. 2A, the anode electrodes 6 formed on the
emitter element forming substrate 1 is made in register with the
aperture pattern 16 for transfer of pixel separation banks of the
screen mask 15, mounted on the screen form plate 14, and the
emitter element forming substrate 1 is set and fixed to the
substrate fixing table 19. In the embodiment, fine holes provided
on the substrate fixing table 19 are made use of to attract and fix
the substrate in reduced pressure.
[0047] Subsequently, the ink 18 is placed on the screen mask 15,
the head 13 lifts the squeegee 11 and lowers the scraper 12 to
bring the same into close contact with the screen mask 15, and
thereafter the scraper 12 is moved to scrape the ink 18 and to fill
the ink 18 into the aperture pattern 16 for transfer of pixel
separation banks and the aperture pattern 17 for transfer of
positioning ribs. In FIG. 2A, the above scraping and filling are
achieved by moving the scraper 12 from right to left.
[0048] As shown in FIG. 2B, the head 13 lifts the scraper 12 and
lowers the squeegee 11 to bring the same into close contact with
the screen mask 15, and thereafter the squeegee 11 is moved from
left to right to transfer the ink 18 filled in the aperture pattern
16 for transfer of pixel separation banks and the aperture pattern
17 for transfer of positioning ribs, to the emitter element forming
substrate 1.
[0049] Thereby, the pixel separation banks 7 are formed in
positions, in which the anode electrodes 6 are partitioned from one
another, and at the same time the positioning ribs 20 being thicker
than the pixel separation banks 7 and having a film thickness
capable of adequately taking effect in serving as a guide for
positioning can be formed on the outer periphery of the emitter
element forming substrate 1.
[0050] FIGS. 3A to 3G are views showing the process of
manufacturing an organic electro-luminescence device according to
the first embodiment of the invention. In FIGS. 3A to 3G, the
reference numeral 21 denotes an external terminal, and 22 a
sealant.
[0051] In the embodiment, the anode electrodes 6 and the external
terminal 21 are first formed on one side of the luminous layer
forming substrate 1 as shown in FIG. 3A. Since emission is taken
out from a side of the cap, the emitter element forming substrate
is not required to be transparent. However, the substrate
preferably assumes the same physical property as the cap. In the
embodiment, since a glass substrate having a high light
transmittance was used for the cap substrate, a glass substrate
(#1737 manufactured by Coring Corporation) of the same quality was
used. Also, in the embodiment, since the emitting layers were
formed to have a 15.2 inch size of the slenderness ratio of 3:4,
the glass substrate was greater 20 mm in respective sides than the
emitting layers to have a size of 348 mm.times.271 mm. Also, the
glass substrate had a thickness of 0.7 mm.
[0052] Since emission is taken out from a side of the cap, the
anode electrodes 6 are also not required to be transparent, and so
metallic materials or the like having a high electric conductivity
can be used for the anode electrodes. Such materials include Cr,
Mo--Ta, Ta, Al or the like. Likewise, materials having a high
electric conductivity are preferably used for the external terminal
21. In the embodiment, the anode electrodes 6 and the external
terminal 21 were formed through exposure and development after
sputtering was used to coat an entire surface with a conductive
material. In addition, the surfaces of the anode electrodes 6 are
preferably smooth. Also, in the embodiment, Al was used to form the
anode electrodes 6 and the external terminal 21.
[0053] Subsequently, the emitter element forming substrate 1 was
held on the substrate fixing table 19 in a manner to have the anode
electrodes 6 and the external terminal 21 facing upward as shown in
FIG. 3B, and the pixel separation banks 7 and the positioning ribs
20 having a greater film thickness than that of the banks were
formed in the same process by means of the method illustrated in
FIG. 2. In addition, materials for the pixel separation banks 7 and
the positioning ribs 20 are the same and include polyimide paste,
maleimide varnish, polyamide, and so on, the materials being
preferably of high thixotropy in terms of shape preserving quality.
Also, the materials are not limited to polyimide but may be ones
having a less hygroscopicity and susceptible of less gas
generation.
[0054] In the embodiment, polyimide PP-2000 for screen printing,
manufactured by Central Glass Corporation was used such that after
coating, it was raised to 220.degree. C. from room temperature at
the rate of 5.degree. C./min in an atmosphere of nitrogen, and
after 220.degree. C. was reached, it was maintained 60 minutes to
be cured. Also, the screen form plate was formed by using No. 500
stainless steel mesh having a wire diameter of 18 .mu.m, an
aperture size of 33 .mu.m and a numerical aperture of 42% and
forming on the mesh an emulsion composed of screen mask forming
photosensitive resin manufactured by Tokyo Process Service
Corporation and having an excellent solvent resistance to form a
pattern.
[0055] In the embodiment, one pixel had a display size of 280 .mu.m
in length and 80 .mu.m in width, and a pitch of 300 .mu.m in length
and 100 .mu.m in width. Since pixel separation banks must cover
other areas than display areas, they have a size of 20 .mu.m in
both length and width, a pitch of widthwise lines being 300 .mu.m,
and a pitch of lengthwise lines being 100 .mu.m. An area, in which
pixel separation banks were formed, had a size of 308 mm.times.231
mm with a diagonal line of 15.2 inches, and the number of pixels
provided therein were 1024.times.3 (three colors of red, green,
blue), that is, a total of 3072 in width and 768 in length. Also,
the thickness of the pixel separation banks is determined by
thickness of respective layers, which constitute emitter elements,
and methods of forming the respective layers.
[0056] Materials for the emitting layers used in the embodiment
comprise a polymer system. Also, the emission contributing layer 8
is composed of hole-transport layer/emitting layers, and the
emitter elements are composed of anode electrodes/hole-transport
layers/emitting layers/cathode electrodes. The anode electrodes 6
and the cathode electrodes 9 were formed by means of sputtering and
deposition, and the hole-transport layers and the emitting layers
were coated by means of ink jet. The anode electrodes and the
cathode electrodes formed by means of sputtering and deposition
were not so much varied in film thickness from immediately after
formation and had a film thickness of around 100 nm.
[0057] Meanwhile, a diluted ink is used since the hole-transport
layers and the emitting layers are coated by means of ink jet.
Therefore, great variation in film thickness is caused immediately
after application and after drying, in which a solvent is
volatilized. In the embodiment, materials being diluted to contain
a solid having a concentration of 3% were used for the
hole-transport layers and the emitting layers having red, green and
blue colors, and the layers, respectively, were set to 0.1 .mu.m in
film thickness after drying, so that the film thickness was 3.3
.mu.m in a non-dried state immediately after application. In the
case where the layers are formed with the use of ink diluted by ink
jet or the like, the thickness of pixel separation banks is
determined by a film thickness immediately after application of the
diluted ink.
[0058] In the embodiment, since the hole-transport layers and the
emitting layers having red, green and blue colors had a thickness
of 3.3 .mu.m immediately after application, pixel separation banks
was made to have a greater film thickness of 5 .mu.m than the above
thickness. When performing application with the line width being 20
.mu.m and the film thickness being 5 .mu.m, an emulsion for
formation of a pattern in the screen form plate is 30 .mu.m.
[0059] In addition, there is a tendency in screen printing that
when a line width is greater than a certain line width, a coating
thickness becomes constant, and when a line width decreases from
the certain line width, a coating thickness decreases as described
previously. With a combination of the materials for pixel
separation banks and the screen form plate, the tendency of coating
thickness relative to a width of apertures in a screen form plate
is varied depending upon whether the width of apertures in a screen
form plate is above or below 150 .mu.m. Preferably, the positioning
ribs 20 have a great thickness in terms of the guiding-quality. In
the case of the above screen form plate, since a line width having
no influence on a film thickness is 150 .mu.m or more, the
positioning ribs 20 were made 200 .mu.m larger than the above film
thickness and had a size of 320 mm.times.243 mm to surround a
region, in which the emitter elements were formed.
[0060] Subsequently, the emission contributing layer 8 was formed
in the pixel separation banks as shown in FIG. 3C. In addition, in
the embodiment, the emitting layers of a polymer system were used
as described above, and the emission contributing layer 8 between
the anode electrodes and the cathode electrodes was composed of
hole-transport layers/emitting layers, each of which were applied
in the banks. Methods of application include a screen printing
method, an ink jet method, and so on, the ink jet method being used
in the embodiment. In addition, the hole-transport layers/emitting
layers were common to all the colors, and a water colloidal
solution (BYTORON P-CH-8000, manufactured by Bayer) containing a
high polymer (3,4-ethylene dioxythiophene) being an electrically
conductive high polymer and a polystyrene sulfonic acid being a
dopant was used as an ink for hole-transport materials.
[0061] Also, used as inks for luminescent materials for emission of
respective colors were Green-K manufactured by Dow Corporation
compounded of 1,2,3,4-tetramethylbenzene for green color, Red-F
manufactured by Dow Corporation compounded of
1,2,3,4-tetramethylbenzene for red color, and Blue-C manufactured
by Dow Corporation compounded of 1,3,5-trimethylbenzene for blue
color. In addition, while the hole-transport layers/emitting layers
were common to all the colors, a material and film thickness may be
changed every color although productivity is decreased.
[0062] Subsequently, the cathode electrodes 9 composed of a light
transmitting conductive material were formed separately every pixel
on a substrate, in which emitting layers of red, green and blue
colors were formed on predetermined banks, by means of sputtering,
as shown in FIG. 3D. In the embodiment, ITO having a sheet
resistivity of about 10 .OMEGA./cm.sup.2 was used as a material for
the cathode electrodes. Since emission is taken out upwardly of the
cathode electrodes, any metallic material permitting no light
transmission cannot be used as a material for the cathode
electrodes and a material having a high light permeability and a
high electric conductivity is preferable.
[0063] Subsequently, the cap outer-periphery surrounding rib 3 was
formed on an outer periphery of the cap substrate 2, being composed
of a light transmitting substrate, in a picture-frame manner as
shown in FIG. 3E, and the absorbent 5 was mounted in a region
surrounded by the cap outer-periphery surrounding rib 3 and in a
range not interfering with a region, in which the emitter element
were formed, when the cap 4 composed of the cap substrate 2 and the
cap outer-periphery surrounding rib 3 was overlapped on the emitter
element forming substrate 1. As illustrated with reference to FIG.
1, the cap substrate 2 preferably has a high light permeability. In
the embodiment, used for the cap substrate 2 was a glass substrate
(#1737 manufactured by Coring Corporation) being of the same
quality as that of the emitter element forming substrate 1 and
having a plate thickness of 0.7 mm and a size of 328 mm.times.251
mm.
[0064] Also, as illustrated with reference to FIG. 1, the absorbent
5 serves to absorb gas generated from the emission contributing
layer 8 of an organic material and outside air and moisture
entering through a sealant after the cap 4 and the emitter element
forming substrate 1 were overlapped and sealed with the use of the
sealant in the succeeding processing. Also, the cap outer-periphery
surrounding rib 3 was sized to have its sides alternately
contacting with the positioning ribs 20 and to have a greater
thickness than the sum of thickness of the positioning ribs 20 and
the absorbent 5. Since the absorbent 5 used in the embodiment had a
thickness of 500 .mu.m and the positioning ribs 20 also used in the
embodiment had a thickness of 30 .mu.m, the cap outer-periphery
surrounding rib 3 was formed to have a thickness of 800 .mu.m
greater than the sum of thickness.
[0065] Methods of forming the cap outer-periphery surrounding rib 3
include a method of straight-writing by means of screen printing,
dispenser or the like, and a method of forming the rib on an entire
surface of the substrate by means of a spinner or the like, and
then removing other portions than an unnecessary periphery in
exposure and development processing. In the embodiment, screen
printing was used to form the cap outer-periphery surrounding rib
having a size of 322 mm.times.245 mm and a line width of 1800 .mu.m
so as to have an inner peripheral side of the cap outer-periphery
surrounding rib 3 contacting with the positioning ribs 20 having a
size of 320 mm.times.243 mm.
[0066] Also, a material for the cap outer-periphery surrounding rib
3 preferably has a good adherence to a surface of the cap
substrate, a less hygroscopicity and is susceptible of less gas
generation, the material itself preferably has a high seal effect,
and an interface between the rib and the cap substrate and the rib
itself are preferably as little pervious as possible to outside air
and moisture. Also, a material having less absorption of
ultraviolet light is used for the cap outer-periphery surrounding
rib so that ultraviolet light is irradiated from a cap side to
enable curing a sealant in the case where an ultraviolet-light
curing material is used for the sealant.
[0067] This makes it possible to irradiate the ultraviolet light on
the sealant more uniformly than irradiation from a side of the
emitter element forming substrate, in which an area shielded by an
external terminal is produced, so that the sealant can cure more
stably in the substrate surfaces. In the embodiment, polyimide
PP-2000 for screen printing, manufactured by Central Glass
Corporation, and being the same as that used for a material for the
pixel separation banks was used for projections on an outer
periphery of the cap.
[0068] Subsequently, the sealant 22 was applied in a position
outside the positioning ribs 20 and opposed to the cap
outer-periphery surrounding rib 3 as shown in FIG. 3F. This
application method includes a dispenser and screen printing. In the
embodiment, a dispenser was used to apply the sealant 22.
[0069] Materials for the sealant include UV (ultraviolet) cure
materials, hot cure materials, and ultraviolet hot cure materials.
In the case of using UV cure materials and ultraviolet hot cure
materials, it is possible that ultraviolet light is scattered and
irradiated on the organic electro-luminescence device in an
area-close to the sealant at the time of ultraviolet irradiation to
generate degradation (reduction in service life) in luminance.
Also, in the case of using hot cure materials, and ultraviolet hot
cure materials, it is possible that when curing is effected at
temperatures above 100.degree. C., the organic electro-luminescence
device is affected to generate degradation (reduction in service
life) in luminance as in the case of ultraviolet. In the
embodiment, used for the sealant was an ultraviolet hot cure
material adapted to be subjected to primary curing by ultraviolet
irradiation and then secondary curing (main curing) by heating at
80.degree. C.
[0070] Subsequently, as shown in FIG. 3G, the self-alignment effect
given by the positioning ribs 20 and the cap outer-periphery
surrounding rib 3 caused the emitter element forming substrate 1
and the cap 4 to be made in registry with each other only by
overlapping, and after effecting shielding sufficient to eliminate
leakage of ultraviolet light to an emitter element forming region,
ultraviolet light was irradiated from outside the cap substrate 2
to cure the sealant 22. At this time, even without lateral
restraint, the cap 4 and the emitter element forming substrate 1 as
overlapped were prevented by the cap outer-periphery surrounding
rib 3 and the positioning ribs 20 from deviating from each
other.
[0071] Subsequently, heating was effected at 80.degree. C. in an
oven to subject the sealant 22 to secondary curing (main curing).
In addition, the operation was wholly carried out in nitrogen being
an inert gas. Since the positioning ribs and the cap
outer-periphery surrounding rib alternately contact with each other
in locations where bonding is effected by the sealant, a bonding
distance (width) of the sealant is made longer than that in the
case of planar surface bonding with the sealant being the same in
width, so that it is possible to prevent outside air and moisture
from entering.
[0072] Subsequently, a display could be fabricated by connecting a
drive circuit to the external terminal 21. The display made it
possible to see a picture image through the cap.
[0073] (Second Embodiment)
[0074] An organic electro-luminescence device was fabricated in the
same manner as in the first embodiment except that the positioning
ribs 20 were arranged outside the cap outer-periphery surrounding
rib 3.
[0075] FIG. 4 is a view showing a final configuration of an organic
electro-luminescence device according to a second embodiment.
[0076] In the embodiment, the cap outer-periphery surrounding rib 3
having a size of 322 mm.times.245 mm and a width of 1800 .mu.m was
formed, the positioning ribs having a size of 324 mm.times.247 mm
and a width of 200 .mu.m was formed, and the positioning ribs 20
was arranged outside the cap outer-periphery surrounding rib 3. At
the time of overlapping the emitter element forming substrate 1 and
the cap 4 together, an inner peripheral side of the positioning
ribs 20 came into contact with an outer peripheral side of the cap
outer-periphery surrounding rib 3 serve as a guide, thus enabling
achieving overlapping with less positional deviation.
[0077] In addition, the positioning ribs 20 was formed to have a
thickness of 800 .mu.m greater than the sum of a thickness of 500
.mu.m of the absorbent and a thickness of about 5.1 .mu.m of the
emitter elements as formed. Also, the sealant 22 was applied on an
inner periphery of the positioning ribs 20 by means of screen
printing, dispenser or the like, and since the sealant was crushed
and spread inward when the emitter element forming substrate 1 and
the cap 4 were overlapped, it was necessary to adjust an amount of
the sealant 22 so that no sealant reached a region where the
emitter elements were formed.
[0078] (Third Embodiment)
[0079] An organic electro-luminescence device was fabricated in the
same manner as in the first embodiment except that the positioning
ribs were doubly formed concentrically, the sealant was applied in
a region surrounded by the ribs, and the cap outer-periphery
surrounding rib was arranged there.
[0080] FIG. 5 is a view showing a final configuration of an organic
electro-luminescence device according to a third embodiment. In
FIG. 5, the reference numeral 35 denotes first positioning ribs,
and 36 second positioning ribs.
[0081] In the embodiment, the cap outer-periphery surrounding rib 3
having a size of 322 mm.times.245 mm and a width of 1800 .mu.m was
formed, the first positioning ribs 35 having a size of 320
mm.times.243 mm and a width of 200 .mu.m was formed, the second
positioning ribs 36 having a size of 324 mm.times.247 mm and a
width of 200 .mu.m was formed, and the cap outer-periphery
surrounding rib 3 was arranged in a region interposed between the
first positioning ribs 35 and the second positioning ribs 36.
[0082] At the time of overlapping the emitter element forming
substrate 1 and the cap 4 together, an outer peripheral side of the
first positioning ribs 35 and an inner peripheral side of the
second positioning ribs 36 came into contact with sides of the cap
outer-periphery surrounding rib 3 to serve as a guide, thus
enabling achieving overlapping with less positional deviation.
[0083] In addition, since the sealant 22 was applied in a region
interposed between the first positioning ribs 35 and the second
positioning ribs 36, even a sealant having a low viscosity could be
used without flowing outside.
[0084] (Fourth Embodiment)
[0085] FIG. 6 is a view showing the process of manufacturing an
organic electro-luminescence device according to a fourth
embodiment.
[0086] In the embodiment, an ITO being a transparent, conductive
material was first applied on an entire one side of the emitter
element forming substrate 1 being a light transmitting substrate by
means of sputtering as shown in FIG. 6A, and anode electrodes 6 and
an external terminal 21 were formed through exposure and
development. In addition, the surfaces of the anode electrodes 6
are preferably smooth. In addition, in the embodiment, ITO as used
had a sheet resistivity of about 10 .OMEGA./cm.sup.2 or less and
surfaces thereof were subjected to smoothening processing.
[0087] Subsequently, the emitter element forming substrate 1 was
held on the substrate fixing table 19 in a manner to have the anode
electrodes 6 and the external terminal 21 facing upward as shown in
FIG. 6B, and the pixel separation banks 7 and the positioning ribs
20 having a greater film thickness than that of the banks were
simultaneously formed by means of the method illustrated in FIG. 2.
In the embodiment, since emission is taken out from a side of the
emitter element forming substrate 1, a drive circuit formed on the
emitter element forming substrate 1 makes interference, so that in
the case where pixels are formed in the same number and in the same
area, a display area becomes smaller in size than that in the case
where emission is taken out from a side of the cap.
[0088] In the embodiment, one pixel had a display size of 180 .mu.m
in length and 80 .mu.m in width, and a pitch of 300 .mu.m in length
and 100 .mu.m in width. Since pixel separation banks must cover
other areas than display areas, they are sized to have a widthwise
line width of 120 .mu.m, and a lengthwise line width of 20 .mu.m,
and a pitch of widthwise lines being 300 .mu.m and a pitch of
lengthwise lines being 100 .mu.m.
[0089] Likewise the first embodiment, an area, in which pixel
separation banks were formed, had a size of 308 mm.times.231 mm
with a diagonal line of 15.2 inches, and the number of pixels
provided therein were 1024.times.3 (three colors of red, green,
blue), that is, a total of 3072 in width and 768 in length. In the
embodiment, since the same hole-transport layers and the same
emitting layers as those in the first embodiment were used, the
pixel separation banks were likewise formed to have a film
thickness of 5 .mu.m. Also, in the embodiment, since the same
screen form and the same plate pixel separation banks as those in
the first embodiment were used, an emulsion for formation of a
pattern in the screen form plate was 30 .mu.m when performing
application with the line width being 20 .mu.m and the film
thickness being 5 .mu.m.
[0090] In addition, there is a tendency in screen printing that
when a line width is greater than a certain line width, a coating
thickness becomes constant, and when a line width decreases from
the certain line width, a coating thickness decreases as described
previously. With a combination of the materials for pixel
separation banks and the screen form plate, the tendency of coating
thickness relative to a width of apertures in a screen form plate
is varied depending upon whether the width of apertures in a screen
form plate is above or below 150 .mu.m. More specifically, when
lengthwise lines having a width of 20 .mu.m and widthwise lines
having a width of 120 .mu.m are formed in a screen form plate
having apertures of the same width, the lengthwise lines having a
width of 20 .mu.m are coated to have a film thickness of around 5
.mu.m while the widthwise lines having a width of 120 .mu.m are
coated to have a film thickness of around 25 .mu.m close to a
thickness of an emulsion for a screen form plate, thus producing a
large difference in film thickness between lengthwise lines and
widthwise lines in the same pixel separation banks.
[0091] Hereupon, in order to make lengthwise lines and widthwise
lines in pixel separation banks uniform, the widthwise lines having
a width of 120 .mu.m are divided into patterns, in which three
widthwise lines having a width of 25 .mu.m were arranged in a
spacing of 22.5 .mu.m, to be printed to be greater in thickness
than the lengthwise lines having a width of 20 .mu.m, and then an
ink was caused to flow into space areas to be leveled, thus filling
the spaces and making the widthwise lines equal in level to the
lengthwise lines. The operation except the above was the same as in
FIG. 3B, and so an explanation therefor is omitted.
[0092] FIG. 6C showing the next processing is the same as FIG. 3C
except that a pixel forming region is small, and so an explanation
therefor is omitted.
[0093] Subsequently, cathode electrodes were separated every pixel
and formed on a substrate, in which emitting layers of red, green
and blue colors were formed on predetermined banks, as shown in
FIG. 6D by means of the vacuum evaporation method. In the
embodiment, Al/Ca was used as a material for the cathode
electrodes. In addition, the material for the cathode electrodes is
not limited to Al/Ca provided that the work function is small.
[0094] Subsequently, the cap outer-periphery surrounding rib 3 was
formed on an outer periphery of the cap substrate 2, being composed
of a light transmitting substrate, in a picture-frame manner as
shown in FIG. 6E, and the absorbent 5 was mounted in a region
surrounded by the cap outer-periphery surrounding rib 3. In the
embodiment, since emission is taken out from a side of the emitter
element forming substrate, the absorbent 5 may be fixed a region,
in which the emitter elements were formed, when the cap was
overlapped on the emitter element forming substrate. Also, it is
possible to use a cap formed by carving an interior of a glass
plate or quartz plate by means of machining or sand blasting and a
cap formed by integral molding of a metallic plate or glass plate
by means of a press or the like.
[0095] In addition, in the case of using a cap formed by means of
machining, press or the like, the positioning ribs 20 must be
dimensionally adjusted to projections on a periphery of the cap so
that when the cap and the emitter element forming substrate are to
be overlapped together, the positioning ribs alternately come into
contact with the projections on the periphery of the cap. Also, a
dispenser and screen printing may be used to further form cap
outer-periphery surrounding ribs on projections on a periphery of a
cap carved by means of machining or a cap formed by means of a
press or the like, and positioning in overlapping may be made by
the use of positioning ribs as a guide.
[0096] FIG. 6F showing the next processing is the same as FIG. 3F,
and so an explanation therefor is omitted.
[0097] Subsequently, as shown in FIG. 6G, the self-alignment effect
given by the positioning ribs 20 and the cap outer-periphery
surrounding rib 3 caused the emitter element forming substrate 1
and the cap 4 to be made in registry with each other only by
overlapping, and after effecting shielding sufficient to eliminate
leakage of ultraviolet light to an emitter element forming region,
ultraviolet light was irradiated from outside the cap substrate to
cure the sealant. Subsequently, heating was effected at 80.degree.
C. in an oven to subject the sealant to secondary curing (main
curing). In addition, the operation was wholly carried out in
nitrogen being an inert gas.
[0098] Subsequently, a display could be fabricated by connecting a
drive circuit to the external terminal 21. The display made it
possible to see a picture image through the emitter element forming
substrate. In addition, while the positioning ribs 20 were mounted
inside the cap outer-periphery surrounding rib 3 in the same manner
as in the first embodiment, the positioning ribs may be configured
in the same manner as in the second and third embodiments.
[0099] (Fifth Embodiment)
[0100] An organic electro-luminescence device was fabricated in the
same manner as in the first, second, third and fourth embodiments
except the use of an ink material having a lower light
transmissivity than that used as a material for pixel separation
banks.
[0101] In the embodiment, a material for pixel separation banks
having a light transmissivity of 0.05% in the range of light
wavelength of 300 to 800 nm and thus having little light
transmitting therethrough was prepared by mixing black ultra-fine
particles NanoTek Black-1 manufactured by CI Kasei Corporation
having a concentration of 3% in volume ratio into polyimide PP-2000
for screen printing, manufactured by Central Glass Corporation and
used as a material for pixel separation banks in the first, second,
third and fourth embodiments. By using the material as a material
for pixel separation banks, entry of light into the pixel
separation banks could be prevented, and a phenomenon of mixing of
emission from adjacent pixels and leakage of light outside from the
pixel separation banks could be prevented. In addition, the device
is not limited to the above material for pixel separation banks and
the black ultra-fine particles, and a material having a lower light
transmissivity is preferable as the material for pixel separation
banks.
[0102] (Sixth Embodiment)
[0103] An organic electro-luminescence device was fabricated in the
method described in one of the first to fifth embodiments except
the use of an emitter element forming substrate formed thereon with
thin-film transistors in place of the emitter element forming
substrate formed thereon with the anode electrodes.
[0104] Thin-film transistors are manufactured through the step of
applying an organo-silicon nano-cluster on a substrate having an
insulating surface, the step of oxidizing the organo-silicon
nano-cluster to form an oxide silicon film, the step of forming an
island non-single crystal silicon film having a source region,
drain region, and a channel region interposed therebetween, the
step of forming a gate insulating film on the island non-single
crystal silicon film, and the step of forming gate electrodes in
the channel region with the gate insulating film therebetween, and
commonly known methods can be used for the respective steps.
[0105] Here, the organo-silicon nano-cluster indicates an organic
silicone compound, which is soluble in organic solvents and has a
band gap of 3 eV to 1.2 eV and which is obtained by reacting a
silane tetrahalide and an organic halide in the existence of alkali
metal and alkaline-earth metal and further processing the same with
hydrofluoric acid. A part of silane tetrahalide may be replaced by
silane trihalide or silane dihalide.
[0106] The organo-silicon nano-cluster thus obtained is soluble in
conventional organic solvents such as hydrocarbon, alcohol, ether,
aromatic solvents, polar solvents, and so on. Also, the processing
with hydrofluoric acid is carried out at the last of composition
whereby oxygen atoms taken into the silicone nano-cluster can be
removed from oxygen, water, and terminator contained in the
reaction system. Such oxygen atoms are not preferable since they
are responsible for creation of silicone oxide films in the case
where silicone thin-films are to be obtained. By performing the
processing with hydrofluoric acid, a silicone nano-cluster as a
precursor for silicone thin-films, containing no oxygen atom can be
obtained.
[0107] Thin films of organo-silicon nano-cluster can be obtained
from a solution with organo-silicon nano-cluster dissolved in a
suitably selected solvent by means of a conventional thin-film
forming method such as wet process including a spin coating method,
dipping method and so on. When the organo-silicon nano-cluster as
deposited is heated or subjected to irradiation of ultraviolet rays
in an atmosphere free of oxygen or reducing atmosphere, silicone
thin films can be obtained, and-when heated or subjected to
irradiation of ultraviolet rays in an oxidizing atmosphere, oxide
silicon thin films can be obtained.
[0108] The above heating and irradiation of ultraviolet rays may be
combined with each other. Also, laser irradiation in an atmosphere
substantially free of oxygen or reducing atmosphere makes it
possible to obtain silicon thin films.
[0109] TFT is formed on an oxide silicon thin film with such
organo-silicon nano-cluster as a precursor. As described above, the
organo-silicon nano-cluster contains silane tetrahalide as a stock
thereof, and the oxide silicon thin film-with the organo-silicon
nano-cluster as a precursor contains halogen. Halogen takes effect
in segregating, catching and getting sodium ions, potassium ions,
and the like to effectively prevent dispersion of impurities into
TFT from a glass substrate. Further, the thicker a film thickness
of the oxide silicon film, the more the effect of prevention of
dispersion of impurities. The organo-silicon nano-cluster can be
deposited by means of the spin coating method, is easy to form a
thick film having a large area, and capable of suppressing
variation of a threshold caused by impurities and eliminating
generation of warp and crack. Therefore, the invention is very
useful in manufacture of an organic electro-luminescence device, in
which a glass substrate having a large area is used.
[0110] Also, the step of oxidizing the organo-silicon nano-cluster
and the step of making the organo-silicon nano-cluster a silicon
thin film without oxidizing the organo-silicon nano-cluster are
suitably combined to be able to form an oxide silicon film in a
manner to have the same surrounding an island silicon layer and its
neighborhood, thus enabling realizing a structure, in which a
difference in level is decreased in ends of an island semiconductor
layer, and preventing reduction in withstand voltage, due to
thin-filming of the gate insulating film. Besides, this technique
can reduce manufacture cost because the island semiconductor layer
and its neighborhood can be formed in a less number of steps than a
conventional island semiconductor layer forming method including
exposure, development and etching.
[0111] The thin-film transistors according to the invention
comprise an oxide silicon film provided on a substrate having an
insulating surface, a plurality of island non-single crystal
semiconductor layers having main surfaces and end surfaces, the
island non-single crystal semiconductor layers having a source
region, drain region, and a channel region, interposed
therebetween, a first insulating film in contact with only the end
surfaces of the island non-single crystal semiconductor layers, a
second insulating film covering the island non-single crystal
semiconductor layers and the first insulating film, and gate
electrodes formed on the channel region with the second insulating
film therebetween, and source electrodes and drain electrodes in
contact with the source region and the drain region, the oxide
silicon film containing halogen.
[0112] Since the island non-single crystal semiconductor layers and
the first insulating film contact with each other only at the end
surfaces, a difference in level is small therebetween to be able to
prevent reduction in withstand voltage, due to thin-filming of the
gate insulating film. Further, since the oxide silicon film
contains halogen, it is possible to effectively prevent entry and
dispersion of impurities into the gate oxide film from a glass
substrate.
[0113] First, an explanation will be given to a method of preparing
an organo-silicon nano-cluster solution. Shaved Mg metal (64 mmol)
as an alkali metal is put in a round bottom flask and heated in a
vacuum at 120.degree. C. to be activated, and after cooling of the
metal, the reaction system is put in a nitrogen atmosphere and a
dehydrated tetrahydrofuran (THF) is added. While applying
ultrasonic waves (60 W) to the semi-product at 0.degree. C.,
tetrachlorosilane (16 mmol) is added for reaction. After reaction
over 2.5 hours, a dark brown reaction liquid generated is made to
react with tert-butyl bromide (16 mmol).
[0114] After reaction for one hour, the reaction liquid is raised
to 50.degree. C. and further caused to make reaction over 0.5 hour.
The reaction liquid is made to dripin distilled water and an
insoluble content is recovered by means of the filtering method.
The recovered insoluble content is dispersed in a 47% hydrof luoric
acid and caused to agitatingly react for 30 minutes, thus providing
another insoluble content by means of filtration. Toluene as a
solvent is used to prepare a 16 weight % solution of the insoluble
content to make the same an organo-silicon nano-cluster
solution.
[0115] A method of forming thin-film transistors on a glass
substrate will be described with reference to FIG. 7.
[0116] The spin coating method with the speed of revolution
adjusted is used to apply the organo-silicon nano-cluster solution
on an emitter element forming substrate 1 (348 mm.times.267 mm)
composed of non-alkali glass having a strain point of 670.degree.
C. to provide for a film thickness of 500 nm, and the solution is
dried on a hot plate at 80.degree. C. for one minute. Thereafter, a
500W ultra-high mercury lamp is used in an oxygen atmosphere to
irradiate ultraviolet rays for 3 minutes to provide an oxide
silicon film (SiO2) 23. Further, the plasma CVD method is used to
accumulate an amorphous silicon layer 50 nm thick. Subsequently,
XeCl excimer laser is irradiated to crystallize the amorphous
silicon layer to provide a polysilicon film.
[0117] Subsequently, a known photo-etching processing is used to
pattern the polysilicon film to provide an island polysilicon layer
24. Thereafter, the plasma CVD method is used to accumulate a SiO2
film, which will make a gate insulating film 25, 70 nm thick, and
further the sputtering method is used to accumulate Nb 250 nm
thick. A known photo-etching processing is used to pattern Nb to
form gate electrodes 26.
[0118] Subsequently, a high-resistance N type polysilicon layer 27
is formed for N channel thin-film transistors with the gate
electrodes 26 as a mask and with the use of ion implantation, and
then a low-resistance N type polysilicon layer 28 is formed with
resist as a mask. Meanwhile, a low-resistance P type polysilicon
layer 29 is formed for P channel thin-film transistors with the
gate electrodes 26 as a mask and with the use of ion
implantation.
[0119] A desirable range of sheet resistance of the high-resistance
polysilicon layer is 20 k.OMEGA. to 100 k.OMEGA., and a desirable
range of sheet resistance of the low-resistance polysilicon layer
is 500 .OMEGA. to 1000 .OMEGA.. Further, an interlayer insulating
film 30 composed of, SiO2 is formed in a manner to cover the whole
layers, and source electrodes 31, drain electrodes 32 and wirings,
which are composed of a three-layer metal film of Ti/Al/Ti, are
formed through contact through holes formed in the interlayer
insulating film 30. Here, the use of the three-layer metal film is
intended for reducing a contact resistance between the
low-resistance polysilicon layer and Al and a contact resistance
between pixel electrodes (ITO) 34 and Al.
[0120] After patterning of the source electrodes 31, drain.
electrodes 32 and wirings, a protective insulating film 33 composed
of Si3N4 and having a film thickness of 500 nm is formed in a
manner to cover the whole layers, and further the pixel electrodes
(ITO) 34 and the source electrodes 31 of the N channel thin film
transistor 28 in a picture image display are connected to each
other through contact through holes formed in the protective
insulating film 33.
[0121] Oxidation of the organo-silicon nano-cluster at the time of
formation of the substrate layer may be made by means of the
heating method or a combination of the ultraviolet ray irradiation
method and the heating method. In this case, irradiation of
ultraviolet rays takes effect in enhancing a throughput, and
heating takes effect in improving a film quality such as minuteness
of a film. Also, not only an oxide silicon film but also a laminate
film of oxide silicon and thin silicon nitride may be used as the
substrate layer. When silicon nitride is used as a buffer layer, it
is possible to effectively prevent entry and dispersion of
impurities into the gate oxide film from a glass substrate.
[0122] A method of crystallizing amorphous silicon may be the solid
growth method making use of thermal annealing and a combination of
thermal annealing and laser annealing. The gate insulating film may
be an oxide film of organo-silicon nano-cluster. Action of halogen
in the film suppresses movements of sodium, potassium, or the like.
Also, the method of accumulating an insulating film such as the
interlayer film, protective film, or the like may be a known
accumulation method such as the plasma CVD method or the like.
Also, materials for the gate, source, and drain electrodes may be a
known electrode material such as Al, Ti, Ta or the like.
[0123] Also, while heating is made at 500.degree. C. in a vacuum
condition (1.times.10.sup.-5 Torr) for one hour prior to
irradiation of XeCl excimer laser, ultraviolet rays may be
irradiated in an atmosphere substantially free of oxygen or
reducing atmosphere, or the both may be combined. Irradiation of
ultraviolet rays takes effect in enhancing a throughput, and
heating takes effect in improving a film quality such as minuteness
of a film. Further, the processing may be omitted, and
crystallization may be effected by laser irradiation in an
atmosphere substantially free of oxygen or reducing atmosphere. In
this case, the processing is simplified and so manufacturing cost
can be reduced.
[0124] Also, the method of oxidizing the organo-silicon
nano-cluster may be heating in an oxidizing atmosphere. In this
case, it is desirable to form an island semiconductor layer prior
to oxidation. A dense film can be obtained by heat treatment after
formation of an island semiconductor layer. A further manufacturing
method of covering portions, which will make an island
semiconductor layer, with a mask, and simultaneously forming the
island semiconductor layer and an insulating film therearound by
means of heating in an oxidizing atmosphere is effective in
simplifying the manufacturing processing. Further, the film quality
of the semiconductor layer is improved by removing a mask and
irradiating ultraviolet rays or laser.
[0125] Since the oxide silicon film or the non-single crystal
silicon film is formed after the organo-silicon nano-cluster is
deposited by means of the spin coating method, the method of
oxidizing is effective in a processing making use of a large-sized
substrate. Also, since the oxide silicon film formed from the
organo-silicon nano-cluster contains halogen, it is possible to
prevent degradation in the characteristics of thin-film transistors
due to impurities in a glass substrate.
[0126] Further, since a construction, in which a difference in
level in ends of an island semiconductor layer is reduced, can be
realized, reduction in withstand voltage, due to thin-filming of
the gate-insulating film can be prevented. This technique can
reduce manufacture cost because the island semiconductor layer and
its neighborhood can be formed in a less number of steps, including
exposure and heating, or only exposure, or the like, than a
conventional island semiconductor layer forming method including
exposure, development and etching. Also, since the island
semiconductor layer and the insulating film therearound contain
halogen, it is possible to prevent degradation in the
characteristics of thin-film transistors due to entry and
dispersion of impurities into the gate insulating film from a glass
substrate.
[0127] The manufacturing method, described above, according to the
invention adopts the spin coating method in place of the
conventional CVD method, and so can reduce electric power at the
time of deposition. Therefore, it is possible to provide a highly
reliable and inexpensive liquid crystal display. Of course, only by
changing the manufacturing method of non-single crystal silicon
film from the conventional CVD method to the spin coating method of
the invention, uniform deposition can be made on a large-sized
substrate and manufacturing cost can be reduced owing to advantages
such as reduction in electric power at the time of deposition, or
the like to provide an inexpensive liquid crystal display.
[0128] In the above deposition, after the organo-silicon
nano-cluster is deposited by means of the spin coating method,
irradiation of ultraviolet rays may be made in an atmosphere
substantially free of oxygen or reducing atmosphere, and heating
may be performed. Further, the both may be combined. Irradiation of
ultraviolet rays takes effect in enhancing a throughput, and
heating takes effect in improving a film quality such as minuteness
of a film. When laser irradiation is further performed after
irradiation of ultraviolet rays or heating, the crystalline quality
of silicone is improved and the characteristics of thin-film
transistors is improved. Further, the processing of irradiation of
ultraviolet rays or heating may be omitted and laser irradiation
maybe performed in an atmosphere substantially free of oxygen or
reducing atmosphere to effect crystallization. In this case,
manufacturing cost can be reduced since the processing is
simplified.
[0129] The method of creating thin-film transistors is not limited
to the embodiment but conventional methods used for liquid crystal
panels will do.
[0130] According to the invention, a cap substrate having a light
transmissivity is used to be bonded to a substrate with emitter
elements to arrange therein an absorbent to afford an organic
electro-luminescence device of high reliability, and pixel
separation banks and positioning ribs are created in the same step
to enable simplification of processing and assembling with high
accuracy.
[0131] While we have shown and described several embodiments in
accordance with our invention, it should be understood that
disclosed embodiments are susceptible of changes and modifications
without departing from the scope of the invention. Therefore, we do
not intend to be bound by the details shown and described herein
but intend to cover all such changes and modifications falling
within the ambit of the appended claims.
* * * * *